Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6: (23 commits)
  sanitize vfsmount refcounting changes
  fix old umount_tree() breakage
  autofs4: Merge the remaining dentry ops tables
  Unexport do_add_mount() and add in follow_automount(), not ->d_automount()
  Allow d_manage() to be used in RCU-walk mode
  Remove a further kludge from __do_follow_link()
  autofs4: Bump version
  autofs4: Add v4 pseudo direct mount support
  autofs4: Fix wait validation
  autofs4: Clean up autofs4_free_ino()
  autofs4: Clean up dentry operations
  autofs4: Clean up inode operations
  autofs4: Remove unused code
  autofs4: Add d_manage() dentry operation
  autofs4: Add d_automount() dentry operation
  Remove the automount through follow_link() kludge code from pathwalk
  CIFS: Use d_automount() rather than abusing follow_link()
  NFS: Use d_automount() rather than abusing follow_link()
  AFS: Use d_automount() rather than abusing follow_link()
  Add an AT_NO_AUTOMOUNT flag to suppress terminal automount
  ...

Documentation/filesystems/Locking

@@ -19,6 +19,8 @@ prototypes:
 	void (*d_release)(struct dentry *);
 	void (*d_iput)(struct dentry *, struct inode *);
 	char *(*d_dname)((struct dentry *dentry, char *buffer, int buflen);
+	struct vfsmount *(*d_automount)(struct path *path);
+	int (*d_manage)(struct dentry *, bool);
 
 locking rules:
 		rename_lock	->d_lock	may block	rcu-walk
@@ -29,6 +31,8 @@ d_delete:	no		yes		no		no
 d_release:	no		no		yes		no
 d_iput:		no		no		yes		no
 d_dname:	no		no		no		no
+d_automount:	no		no		yes		no
+d_manage:	no		no		yes (ref-walk)	maybe
 
 --------------------------- inode_operations --------------------------- 
 prototypes:

Documentation/filesystems/vfs.txt

@@ -864,6 +864,8 @@ struct dentry_operations {
 	void (*d_release)(struct dentry *);
 	void (*d_iput)(struct dentry *, struct inode *);
 	char *(*d_dname)(struct dentry *, char *, int);
+	struct vfsmount *(*d_automount)(struct path *);
+	int (*d_manage)(struct dentry *, bool, bool);
 };
 
   d_revalidate: called when the VFS needs to revalidate a dentry. This
@@ -930,6 +932,47 @@ struct dentry_operations {
 	at the end of the buffer, and returns a pointer to the first char.
 	dynamic_dname() helper function is provided to take care of this.
 
+  d_automount: called when an automount dentry is to be traversed (optional).
+	This should create a new VFS mount record and return the record to the
+	caller.  The caller is supplied with a path parameter giving the
+	automount directory to describe the automount target and the parent
+	VFS mount record to provide inheritable mount parameters.  NULL should
+	be returned if someone else managed to make the automount first.  If
+	the vfsmount creation failed, then an error code should be returned.
+	If -EISDIR is returned, then the directory will be treated as an
+	ordinary directory and returned to pathwalk to continue walking.
+
+	If a vfsmount is returned, the caller will attempt to mount it on the
+	mountpoint and will remove the vfsmount from its expiration list in
+	the case of failure.  The vfsmount should be returned with 2 refs on
+	it to prevent automatic expiration - the caller will clean up the
+	additional ref.
+
+	This function is only used if DCACHE_NEED_AUTOMOUNT is set on the
+	dentry.  This is set by __d_instantiate() if S_AUTOMOUNT is set on the
+	inode being added.
+
+  d_manage: called to allow the filesystem to manage the transition from a
+	dentry (optional).  This allows autofs, for example, to hold up clients
+	waiting to explore behind a 'mountpoint' whilst letting the daemon go
+	past and construct the subtree there.  0 should be returned to let the
+	calling process continue.  -EISDIR can be returned to tell pathwalk to
+	use this directory as an ordinary directory and to ignore anything
+	mounted on it and not to check the automount flag.  Any other error
+	code will abort pathwalk completely.
+
+	If the 'mounting_here' parameter is true, then namespace_sem is being
+	held by the caller and the function should not initiate any mounts or
+	unmounts that it will then wait for.
+
+	If the 'rcu_walk' parameter is true, then the caller is doing a
+	pathwalk in RCU-walk mode.  Sleeping is not permitted in this mode,
+	and the caller can be asked to leave it and call again by returing
+	-ECHILD.
+
+	This function is only used if DCACHE_MANAGE_TRANSIT is set on the
+	dentry being transited from.
+
 Example :
 
 static char *pipefs_dname(struct dentry *dent, char *buffer, int buflen)

drivers/mtd/mtdchar.c

@@ -1201,7 +1201,7 @@ err_unregister_chdev:
 static void __exit cleanup_mtdchar(void)
 {
 	unregister_mtd_user(&mtdchar_notifier);
-	mntput_long(mtd_inode_mnt);
+	mntput(mtd_inode_mnt);
 	unregister_filesystem(&mtd_inodefs_type);
 	__unregister_chrdev(MTD_CHAR_MAJOR, 0, 1 << MINORBITS, "mtd");
 }

drivers/staging/autofs/dirhash.c

@@ -88,14 +88,13 @@ struct autofs_dir_ent *autofs_expire(struct super_block *sb,
 		}
 		path.mnt = mnt;
 		path_get(&path);
-		if (!follow_down(&path)) {
+		if (!follow_down_one(&path)) {
 			path_put(&path);
 			DPRINTK(("autofs: not expirable\
 			(not a mounted directory): %s\n", ent->name));
 			continue;
 		}
-		while (d_mountpoint(path.dentry) && follow_down(&path))
-			;
+		follow_down(&path, false);  // TODO: need to check error
 		umount_ok = may_umount(path.mnt);
 		path_put(&path);
 

fs/afs/dir.c

@@ -66,6 +66,7 @@ const struct dentry_operations afs_fs_dentry_operations = {
 	.d_revalidate	= afs_d_revalidate,
 	.d_delete	= afs_d_delete,
 	.d_release	= afs_d_release,
+	.d_automount	= afs_d_automount,
 };
 
 #define AFS_DIR_HASHTBL_SIZE	128

fs/afs/inode.c

@@ -184,7 +184,8 @@ struct inode *afs_iget_autocell(struct inode *dir, const char *dev_name,
 	inode->i_generation	= 0;
 
 	set_bit(AFS_VNODE_PSEUDODIR, &vnode->flags);
-	inode->i_flags |= S_NOATIME;
+	set_bit(AFS_VNODE_MOUNTPOINT, &vnode->flags);
+	inode->i_flags |= S_AUTOMOUNT | S_NOATIME;
 	unlock_new_inode(inode);
 	_leave(" = %p", inode);
 	return inode;

fs/afs/internal.h

@@ -592,6 +592,7 @@ extern const struct inode_operations afs_mntpt_inode_operations;
 extern const struct inode_operations afs_autocell_inode_operations;
 extern const struct file_operations afs_mntpt_file_operations;
 
+extern struct vfsmount *afs_d_automount(struct path *);
 extern int afs_mntpt_check_symlink(struct afs_vnode *, struct key *);
 extern void afs_mntpt_kill_timer(void);
 

fs/afs/mntpt.c

@@ -24,7 +24,6 @@ static struct dentry *afs_mntpt_lookup(struct inode *dir,
 				       struct dentry *dentry,
 				       struct nameidata *nd);
 static int afs_mntpt_open(struct inode *inode, struct file *file);
-static void *afs_mntpt_follow_link(struct dentry *dentry, struct nameidata *nd);
 static void afs_mntpt_expiry_timed_out(struct work_struct *work);
 
 const struct file_operations afs_mntpt_file_operations = {
@@ -34,13 +33,11 @@ const struct file_operations afs_mntpt_file_operations = {
 
 const struct inode_operations afs_mntpt_inode_operations = {
 	.lookup		= afs_mntpt_lookup,
-	.follow_link	= afs_mntpt_follow_link,
 	.readlink	= page_readlink,
 	.getattr	= afs_getattr,
 };
 
 const struct inode_operations afs_autocell_inode_operations = {
-	.follow_link	= afs_mntpt_follow_link,
 	.getattr	= afs_getattr,
 };
 
@@ -88,6 +85,7 @@ int afs_mntpt_check_symlink(struct afs_vnode *vnode, struct key *key)
 		_debug("symlink is a mountpoint");
 		spin_lock(&vnode->lock);
 		set_bit(AFS_VNODE_MOUNTPOINT, &vnode->flags);
+		vnode->vfs_inode.i_flags |= S_AUTOMOUNT;
 		spin_unlock(&vnode->lock);
 	}
 
@@ -238,52 +236,24 @@ error_no_devname:
 }
 
 /*
- * follow a link from a mountpoint directory, thus causing it to be mounted
+ * handle an automount point
  */
-static void *afs_mntpt_follow_link(struct dentry *dentry, struct nameidata *nd)
+struct vfsmount *afs_d_automount(struct path *path)
 {
 	struct vfsmount *newmnt;
-	int err;
 
-	_enter("%p{%s},{%s:%p{%s},}",
-	       dentry,
-	       dentry->d_name.name,
-	       nd->path.mnt->mnt_devname,
-	       dentry,
-	       nd->path.dentry->d_name.name);
+	_enter("{%s,%s}", path->mnt->mnt_devname, path->dentry->d_name.name);
 
-	dput(nd->path.dentry);
-	nd->path.dentry = dget(dentry);
+	newmnt = afs_mntpt_do_automount(path->dentry);
+	if (IS_ERR(newmnt))
+		return newmnt;
 
-	newmnt = afs_mntpt_do_automount(nd->path.dentry);
-	if (IS_ERR(newmnt)) {
-		path_put(&nd->path);
-		return (void *)newmnt;
-	}
-
-	mntget(newmnt);
-	err = do_add_mount(newmnt, &nd->path, MNT_SHRINKABLE, &afs_vfsmounts);
-	switch (err) {
-	case 0:
-		path_put(&nd->path);
-		nd->path.mnt = newmnt;
-		nd->path.dentry = dget(newmnt->mnt_root);
-		queue_delayed_work(afs_wq, &afs_mntpt_expiry_timer,
-				   afs_mntpt_expiry_timeout * HZ);
-		break;
-	case -EBUSY:
-		/* someone else made a mount here whilst we were busy */
-		while (d_mountpoint(nd->path.dentry) &&
-		       follow_down(&nd->path))
-			;
-		err = 0;
-	default:
-		mntput(newmnt);
-		break;
-	}
-
-	_leave(" = %d", err);
-	return ERR_PTR(err);
+	mntget(newmnt); /* prevent immediate expiration */
+	mnt_set_expiry(newmnt, &afs_vfsmounts);
+	queue_delayed_work(afs_wq, &afs_mntpt_expiry_timer,
+			   afs_mntpt_expiry_timeout * HZ);
+	_leave(" = %p {%s}", newmnt, newmnt->mnt_devname);
+	return newmnt;
 }
 
 /*

fs/anon_inodes.c

@@ -233,7 +233,7 @@ static int __init anon_inode_init(void)
 	return 0;
 
 err_mntput:
-	mntput_long(anon_inode_mnt);
+	mntput(anon_inode_mnt);
 err_unregister_filesystem:
 	unregister_filesystem(&anon_inode_fs_type);
 err_exit:

fs/autofs4/autofs_i.h

@@ -99,7 +99,6 @@ struct autofs_info {
 };
 
 #define AUTOFS_INF_EXPIRING	(1<<0) /* dentry is in the process of expiring */
-#define AUTOFS_INF_MOUNTPOINT	(1<<1) /* mountpoint status for direct expire */
 #define AUTOFS_INF_PENDING	(1<<2) /* dentry pending mount */
 
 struct autofs_wait_queue {
@@ -176,13 +175,6 @@ static inline int autofs4_ispending(struct dentry *dentry)
 	return 0;
 }
 
-static inline void autofs4_copy_atime(struct file *src, struct file *dst)
-{
-	dst->f_path.dentry->d_inode->i_atime =
-		src->f_path.dentry->d_inode->i_atime;
-	return;
-}
-
 struct inode *autofs4_get_inode(struct super_block *, struct autofs_info *);
 void autofs4_free_ino(struct autofs_info *);
 
@@ -212,11 +204,83 @@ void autofs_dev_ioctl_exit(void);
 
 extern const struct inode_operations autofs4_symlink_inode_operations;
 extern const struct inode_operations autofs4_dir_inode_operations;
-extern const struct inode_operations autofs4_root_inode_operations;
-extern const struct inode_operations autofs4_indirect_root_inode_operations;
-extern const struct inode_operations autofs4_direct_root_inode_operations;
 extern const struct file_operations autofs4_dir_operations;
 extern const struct file_operations autofs4_root_operations;
+extern const struct dentry_operations autofs4_dentry_operations;
+
+/* VFS automount flags management functions */
+
+static inline void __managed_dentry_set_automount(struct dentry *dentry)
+{
+	dentry->d_flags |= DCACHE_NEED_AUTOMOUNT;
+}
+
+static inline void managed_dentry_set_automount(struct dentry *dentry)
+{
+	spin_lock(&dentry->d_lock);
+	__managed_dentry_set_automount(dentry);
+	spin_unlock(&dentry->d_lock);
+}
+
+static inline void __managed_dentry_clear_automount(struct dentry *dentry)
+{
+	dentry->d_flags &= ~DCACHE_NEED_AUTOMOUNT;
+}
+
+static inline void managed_dentry_clear_automount(struct dentry *dentry)
+{
+	spin_lock(&dentry->d_lock);
+	__managed_dentry_clear_automount(dentry);
+	spin_unlock(&dentry->d_lock);
+}
+
+static inline void __managed_dentry_set_transit(struct dentry *dentry)
+{
+	dentry->d_flags |= DCACHE_MANAGE_TRANSIT;
+}
+
+static inline void managed_dentry_set_transit(struct dentry *dentry)
+{
+	spin_lock(&dentry->d_lock);
+	__managed_dentry_set_transit(dentry);
+	spin_unlock(&dentry->d_lock);
+}
+
+static inline void __managed_dentry_clear_transit(struct dentry *dentry)
+{
+	dentry->d_flags &= ~DCACHE_MANAGE_TRANSIT;
+}
+
+static inline void managed_dentry_clear_transit(struct dentry *dentry)
+{
+	spin_lock(&dentry->d_lock);
+	__managed_dentry_clear_transit(dentry);
+	spin_unlock(&dentry->d_lock);
+}
+
+static inline void __managed_dentry_set_managed(struct dentry *dentry)
+{
+	dentry->d_flags |= (DCACHE_NEED_AUTOMOUNT|DCACHE_MANAGE_TRANSIT);
+}
+
+static inline void managed_dentry_set_managed(struct dentry *dentry)
+{
+	spin_lock(&dentry->d_lock);
+	__managed_dentry_set_managed(dentry);
+	spin_unlock(&dentry->d_lock);
+}
+
+static inline void __managed_dentry_clear_managed(struct dentry *dentry)
+{
+	dentry->d_flags &= ~(DCACHE_NEED_AUTOMOUNT|DCACHE_MANAGE_TRANSIT);
+}
+
+static inline void managed_dentry_clear_managed(struct dentry *dentry)
+{
+	spin_lock(&dentry->d_lock);
+	__managed_dentry_clear_managed(dentry);
+	spin_unlock(&dentry->d_lock);
+}
 
 /* Initializing function */
 
@@ -229,19 +293,6 @@ int autofs4_wait(struct autofs_sb_info *,struct dentry *, enum autofs_notify);
 int autofs4_wait_release(struct autofs_sb_info *,autofs_wqt_t,int);
 void autofs4_catatonic_mode(struct autofs_sb_info *);
 
-static inline int autofs4_follow_mount(struct path *path)
-{
-	int res = 0;
-
-	while (d_mountpoint(path->dentry)) {
-		int followed = follow_down(path);
-		if (!followed)
-			break;
-		res = 1;
-	}
-	return res;
-}
-
 static inline u32 autofs4_get_dev(struct autofs_sb_info *sbi)
 {
 	return new_encode_dev(sbi->sb->s_dev);

fs/autofs4/dev-ioctl.c

@@ -551,7 +551,7 @@ static int autofs_dev_ioctl_ismountpoint(struct file *fp,
 
 		err = have_submounts(path.dentry);
 
-		if (follow_down(&path))
+		if (follow_down_one(&path))
 			magic = path.mnt->mnt_sb->s_magic;
 	}
 

fs/autofs4/expire.c

@@ -26,10 +26,6 @@ static inline int autofs4_can_expire(struct dentry *dentry,
 	if (ino == NULL)
 		return 0;
 
-	/* No point expiring a pending mount */
-	if (ino->flags & AUTOFS_INF_PENDING)
-		return 0;
-
 	if (!do_now) {
 		/* Too young to die */
 		if (!timeout || time_after(ino->last_used + timeout, now))
@@ -56,7 +52,7 @@ static int autofs4_mount_busy(struct vfsmount *mnt, struct dentry *dentry)
 
 	path_get(&path);
 
-	if (!follow_down(&path))
+	if (!follow_down_one(&path))
 		goto done;
 
 	if (is_autofs4_dentry(path.dentry)) {
@@ -283,6 +279,7 @@ struct dentry *autofs4_expire_direct(struct super_block *sb,
 	unsigned long timeout;
 	struct dentry *root = dget(sb->s_root);
 	int do_now = how & AUTOFS_EXP_IMMEDIATE;
+	struct autofs_info *ino;
 
 	if (!root)
 		return NULL;
@@ -291,19 +288,21 @@ struct dentry *autofs4_expire_direct(struct super_block *sb,
 	timeout = sbi->exp_timeout;
 
 	spin_lock(&sbi->fs_lock);
+	ino = autofs4_dentry_ino(root);
+	/* No point expiring a pending mount */
+	if (ino->flags & AUTOFS_INF_PENDING) {
+		spin_unlock(&sbi->fs_lock);
+		return NULL;
+	}
+	managed_dentry_set_transit(root);
 	if (!autofs4_direct_busy(mnt, root, timeout, do_now)) {
 		struct autofs_info *ino = autofs4_dentry_ino(root);
-		if (d_mountpoint(root)) {
-			ino->flags |= AUTOFS_INF_MOUNTPOINT;
-			spin_lock(&root->d_lock);
-			root->d_flags &= ~DCACHE_MOUNTED;
-			spin_unlock(&root->d_lock);
-		}
 		ino->flags |= AUTOFS_INF_EXPIRING;
 		init_completion(&ino->expire_complete);
 		spin_unlock(&sbi->fs_lock);
 		return root;
 	}
+	managed_dentry_clear_transit(root);
 	spin_unlock(&sbi->fs_lock);
 	dput(root);
 
@@ -340,6 +339,10 @@ struct dentry *autofs4_expire_indirect(struct super_block *sb,
 	while ((dentry = get_next_positive_dentry(dentry, root))) {
 		spin_lock(&sbi->fs_lock);
 		ino = autofs4_dentry_ino(dentry);
+		/* No point expiring a pending mount */
+		if (ino->flags & AUTOFS_INF_PENDING)
+			goto cont;
+		managed_dentry_set_transit(dentry);
 
 		/*
 		 * Case 1: (i) indirect mount or top level pseudo direct mount
@@ -399,6 +402,8 @@ struct dentry *autofs4_expire_indirect(struct super_block *sb,
 			}
 		}
 next:
+		managed_dentry_clear_transit(dentry);
+cont:
 		spin_unlock(&sbi->fs_lock);
 	}
 	return NULL;
@@ -479,6 +484,8 @@ int autofs4_expire_run(struct super_block *sb,
 	spin_lock(&sbi->fs_lock);
 	ino = autofs4_dentry_ino(dentry);
 	ino->flags &= ~AUTOFS_INF_EXPIRING;
+	if (!d_unhashed(dentry))
+		managed_dentry_clear_transit(dentry);
 	complete_all(&ino->expire_complete);
 	spin_unlock(&sbi->fs_lock);
 
@@ -504,18 +511,18 @@ int autofs4_do_expire_multi(struct super_block *sb, struct vfsmount *mnt,
 		ret = autofs4_wait(sbi, dentry, NFY_EXPIRE);
 
 		spin_lock(&sbi->fs_lock);
-		if (ino->flags & AUTOFS_INF_MOUNTPOINT) {
-			spin_lock(&sb->s_root->d_lock);
-			/*
-			 * If we haven't been expired away, then reset
-			 * mounted status.
-			 */
-			if (mnt->mnt_parent != mnt)
-				sb->s_root->d_flags |= DCACHE_MOUNTED;
-			spin_unlock(&sb->s_root->d_lock);
-			ino->flags &= ~AUTOFS_INF_MOUNTPOINT;
-		}
 		ino->flags &= ~AUTOFS_INF_EXPIRING;
+		spin_lock(&dentry->d_lock);
+		if (ret)
+			__managed_dentry_clear_transit(dentry);
+		else {
+			if ((IS_ROOT(dentry) ||
+			    (autofs_type_indirect(sbi->type) &&
+			     IS_ROOT(dentry->d_parent))) &&
+			    !(dentry->d_flags & DCACHE_NEED_AUTOMOUNT))
+				__managed_dentry_set_automount(dentry);
+		}
+		spin_unlock(&dentry->d_lock);
 		complete_all(&ino->expire_complete);
 		spin_unlock(&sbi->fs_lock);
 		dput(dentry);

fs/autofs4/inode.c

@@ -45,7 +45,6 @@ struct autofs_info *autofs4_init_ino(struct autofs_info *ino,
 
 	if (!reinit) {
 		ino->flags = 0;
-		ino->inode = NULL;
 		ino->dentry = NULL;
 		ino->size = 0;
 		INIT_LIST_HEAD(&ino->active);
@@ -76,19 +75,8 @@ struct autofs_info *autofs4_init_ino(struct autofs_info *ino,
 
 void autofs4_free_ino(struct autofs_info *ino)
 {
-	struct autofs_info *p_ino;
-
 	if (ino->dentry) {
 		ino->dentry->d_fsdata = NULL;
-		if (ino->dentry->d_inode) {
-			struct dentry *parent = ino->dentry->d_parent;
-			if (atomic_dec_and_test(&ino->count)) {
-				p_ino = autofs4_dentry_ino(parent);
-				if (p_ino && parent != ino->dentry)
-					atomic_dec(&p_ino->count);
-			}
-			dput(ino->dentry);
-		}
 		ino->dentry = NULL;
 	}
 	if (ino->free)
@@ -251,10 +239,6 @@ static struct autofs_info *autofs4_mkroot(struct autofs_sb_info *sbi)
 	return ino;
 }
 
-static const struct dentry_operations autofs4_sb_dentry_operations = {
-	.d_release      = autofs4_dentry_release,
-};
-
 int autofs4_fill_super(struct super_block *s, void *data, int silent)
 {
 	struct inode * root_inode;
@@ -292,6 +276,7 @@ int autofs4_fill_super(struct super_block *s, void *data, int silent)
 	s->s_blocksize_bits = 10;
 	s->s_magic = AUTOFS_SUPER_MAGIC;
 	s->s_op = &autofs4_sops;
+	s->s_d_op = &autofs4_dentry_operations;
 	s->s_time_gran = 1;
 
 	/*
@@ -309,7 +294,6 @@ int autofs4_fill_super(struct super_block *s, void *data, int silent)
 		goto fail_iput;
 	pipe = NULL;
 
-	d_set_d_op(root, &autofs4_sb_dentry_operations);
 	root->d_fsdata = ino;
 
 	/* Can this call block? */
@@ -320,10 +304,11 @@ int autofs4_fill_super(struct super_block *s, void *data, int silent)
 		goto fail_dput;
 	}
 
+	if (autofs_type_trigger(sbi->type))
+		__managed_dentry_set_managed(root);
+
 	root_inode->i_fop = &autofs4_root_operations;
-	root_inode->i_op = autofs_type_trigger(sbi->type) ?
-			&autofs4_direct_root_inode_operations :
-			&autofs4_indirect_root_inode_operations;
+	root_inode->i_op = &autofs4_dir_inode_operations;
 
 	/* Couldn't this be tested earlier? */
 	if (sbi->max_proto < AUTOFS_MIN_PROTO_VERSION ||
@@ -391,7 +376,6 @@ struct inode *autofs4_get_inode(struct super_block *sb,
 	if (inode == NULL)
 		return NULL;
 
-	inf->inode = inode;
 	inode->i_mode = inf->mode;
 	if (sb->s_root) {
 		inode->i_uid = sb->s_root->d_inode->i_uid;

fs/autofs4/waitq.c

@@ -309,6 +309,9 @@ static int validate_request(struct autofs_wait_queue **wait,
 	 * completed while we waited on the mutex ...
 	 */
 	if (notify == NFY_MOUNT) {
+		struct dentry *new = NULL;
+		int valid = 1;
+
 		/*
 		 * If the dentry was successfully mounted while we slept
 		 * on the wait queue mutex we can return success. If it
@@ -316,8 +319,20 @@ static int validate_request(struct autofs_wait_queue **wait,
 		 * a multi-mount with no mount at it's base) we can
 		 * continue on and create a new request.
 		 */
+		if (!IS_ROOT(dentry)) {
+			if (dentry->d_inode && d_unhashed(dentry)) {
+				struct dentry *parent = dentry->d_parent;
+				new = d_lookup(parent, &dentry->d_name);
+				if (new)
+					dentry = new;
+			}
+		}
 		if (have_submounts(dentry))
-			return 0;
+			valid = 0;
+
+		if (new)
+			dput(new);
+		return valid;
 	}
 
 	return 1;

fs/cifs/cifs_dfs_ref.c

@@ -255,35 +255,6 @@ static struct vfsmount *cifs_dfs_do_refmount(struct cifs_sb_info *cifs_sb,
 
 }
 
-static int add_mount_helper(struct vfsmount *newmnt, struct nameidata *nd,
-				struct list_head *mntlist)
-{
-	/* stolen from afs code */
-	int err;
-
-	mntget(newmnt);
-	err = do_add_mount(newmnt, &nd->path, nd->path.mnt->mnt_flags | MNT_SHRINKABLE, mntlist);
-	switch (err) {
-	case 0:
-		path_put(&nd->path);
-		nd->path.mnt = newmnt;
-		nd->path.dentry = dget(newmnt->mnt_root);
-		schedule_delayed_work(&cifs_dfs_automount_task,
-				      cifs_dfs_mountpoint_expiry_timeout);
-		break;
-	case -EBUSY:
-		/* someone else made a mount here whilst we were busy */
-		while (d_mountpoint(nd->path.dentry) &&
-		       follow_down(&nd->path))
-			;
-		err = 0;
-	default:
-		mntput(newmnt);
-		break;
-	}
-	return err;
-}
-
 static void dump_referral(const struct dfs_info3_param *ref)
 {
 	cFYI(1, "DFS: ref path: %s", ref->path_name);
@@ -293,45 +264,43 @@ static void dump_referral(const struct dfs_info3_param *ref)
 				ref->path_consumed);
 }
 
-
-static void*
-cifs_dfs_follow_mountpoint(struct dentry *dentry, struct nameidata *nd)
+/*
+ * Create a vfsmount that we can automount
+ */
+static struct vfsmount *cifs_dfs_do_automount(struct dentry *mntpt)
 {
 	struct dfs_info3_param *referrals = NULL;
 	unsigned int num_referrals = 0;
 	struct cifs_sb_info *cifs_sb;
 	struct cifsSesInfo *ses;
-	char *full_path = NULL;
+	char *full_path;
 	int xid, i;
-	int rc = 0;
-	struct vfsmount *mnt = ERR_PTR(-ENOENT);
+	int rc;
+	struct vfsmount *mnt;
 	struct tcon_link *tlink;
 
 	cFYI(1, "in %s", __func__);
-	BUG_ON(IS_ROOT(dentry));
+	BUG_ON(IS_ROOT(mntpt));
 
 	xid = GetXid();
 
-	dput(nd->path.dentry);
-	nd->path.dentry = dget(dentry);
-
 	/*
 	 * The MSDFS spec states that paths in DFS referral requests and
 	 * responses must be prefixed by a single '\' character instead of
 	 * the double backslashes usually used in the UNC. This function
 	 * gives us the latter, so we must adjust the result.
 	 */
-	full_path = build_path_from_dentry(dentry);
-	if (full_path == NULL) {
-		rc = -ENOMEM;
-		goto out_err;
-	}
+	mnt = ERR_PTR(-ENOMEM);
+	full_path = build_path_from_dentry(mntpt);
+	if (full_path == NULL)
+		goto free_xid;
 
-	cifs_sb = CIFS_SB(dentry->d_inode->i_sb);
+	cifs_sb = CIFS_SB(mntpt->d_inode->i_sb);
 	tlink = cifs_sb_tlink(cifs_sb);
+	mnt = ERR_PTR(-EINVAL);
 	if (IS_ERR(tlink)) {
-		rc = PTR_ERR(tlink);
-		goto out_err;
+		mnt = ERR_CAST(tlink);
+		goto free_full_path;
 	}
 	ses = tlink_tcon(tlink)->ses;
 
@@ -341,46 +310,63 @@ cifs_dfs_follow_mountpoint(struct dentry *dentry, struct nameidata *nd)
 
 	cifs_put_tlink(tlink);
 
+	mnt = ERR_PTR(-ENOENT);
 	for (i = 0; i < num_referrals; i++) {
 		int len;
-		dump_referral(referrals+i);
+		dump_referral(referrals + i);
 		/* connect to a node */
 		len = strlen(referrals[i].node_name);
 		if (len < 2) {
 			cERROR(1, "%s: Net Address path too short: %s",
 					__func__, referrals[i].node_name);
-			rc = -EINVAL;
-			goto out_err;
+			mnt = ERR_PTR(-EINVAL);
+			break;
 		}
 		mnt = cifs_dfs_do_refmount(cifs_sb,
 				full_path, referrals + i);
 		cFYI(1, "%s: cifs_dfs_do_refmount:%s , mnt:%p", __func__,
 					referrals[i].node_name, mnt);
-
-		/* complete mount procedure if we accured submount */
 		if (!IS_ERR(mnt))
-			break;
+			goto success;
 	}
 
-	/* we need it cause for() above could exit without valid submount */
-	rc = PTR_ERR(mnt);
-	if (IS_ERR(mnt))
-		goto out_err;
+	/* no valid submounts were found; return error from get_dfs_path() by
+	 * preference */
+	if (rc != 0)
+		mnt = ERR_PTR(rc);
 
-	rc = add_mount_helper(mnt, nd, &cifs_dfs_automount_list);
-
-out:
-	FreeXid(xid);
+success:
 	free_dfs_info_array(referrals, num_referrals);
+free_full_path:
 	kfree(full_path);
+free_xid:
+	FreeXid(xid);
 	cFYI(1, "leaving %s" , __func__);
-	return ERR_PTR(rc);
-out_err:
-	path_put(&nd->path);
-	goto out;
+	return mnt;
+}
+
+/*
+ * Attempt to automount the referral
+ */
+struct vfsmount *cifs_dfs_d_automount(struct path *path)
+{
+	struct vfsmount *newmnt;
+
+	cFYI(1, "in %s", __func__);
+
+	newmnt = cifs_dfs_do_automount(path->dentry);
+	if (IS_ERR(newmnt)) {
+		cFYI(1, "leaving %s [automount failed]" , __func__);
+		return newmnt;
+	}
+
+	mntget(newmnt); /* prevent immediate expiration */
+	mnt_set_expiry(newmnt, &cifs_dfs_automount_list);
+	schedule_delayed_work(&cifs_dfs_automount_task,
+			      cifs_dfs_mountpoint_expiry_timeout);
+	cFYI(1, "leaving %s [ok]" , __func__);
+	return newmnt;
 }
 
 const struct inode_operations cifs_dfs_referral_inode_operations = {
-	.follow_link = cifs_dfs_follow_mountpoint,
 };
-

fs/cifs/cifsfs.h

@@ -93,6 +93,12 @@ extern int cifs_readdir(struct file *file, void *direntry, filldir_t filldir);
 extern const struct dentry_operations cifs_dentry_ops;
 extern const struct dentry_operations cifs_ci_dentry_ops;
 
+#ifdef CONFIG_CIFS_DFS_UPCALL
+extern struct vfsmount *cifs_dfs_d_automount(struct path *path);
+#else
+#define cifs_dfs_d_automount NULL
+#endif
+
 /* Functions related to symlinks */
 extern void *cifs_follow_link(struct dentry *direntry, struct nameidata *nd);
 extern void cifs_put_link(struct dentry *direntry,

fs/cifs/dir.c

@@ -675,6 +675,7 @@ cifs_d_revalidate(struct dentry *direntry, struct nameidata *nd)
 
 const struct dentry_operations cifs_dentry_ops = {
 	.d_revalidate = cifs_d_revalidate,
+	.d_automount = cifs_dfs_d_automount,
 /* d_delete:       cifs_d_delete,      */ /* not needed except for debugging */
 };
 
@@ -711,4 +712,5 @@ const struct dentry_operations cifs_ci_dentry_ops = {
 	.d_revalidate = cifs_d_revalidate,
 	.d_hash = cifs_ci_hash,
 	.d_compare = cifs_ci_compare,
+	.d_automount = cifs_dfs_d_automount,
 };

fs/cifs/inode.c

@@ -32,7 +32,7 @@
 #include "fscache.h"
 
 
-static void cifs_set_ops(struct inode *inode, const bool is_dfs_referral)
+static void cifs_set_ops(struct inode *inode)
 {
 	struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
 
@@ -60,7 +60,7 @@ static void cifs_set_ops(struct inode *inode, const bool is_dfs_referral)
 		break;
 	case S_IFDIR:
 #ifdef CONFIG_CIFS_DFS_UPCALL
-		if (is_dfs_referral) {
+		if (IS_AUTOMOUNT(inode)) {
 			inode->i_op = &cifs_dfs_referral_inode_operations;
 		} else {
 #else /* NO DFS support, treat as a directory */
@@ -167,7 +167,9 @@ cifs_fattr_to_inode(struct inode *inode, struct cifs_fattr *fattr)
 	}
 	spin_unlock(&inode->i_lock);
 
-	cifs_set_ops(inode, fattr->cf_flags & CIFS_FATTR_DFS_REFERRAL);
+	if (fattr->cf_flags & CIFS_FATTR_DFS_REFERRAL)
+		inode->i_flags |= S_AUTOMOUNT;
+	cifs_set_ops(inode);
 }
 
 void

fs/dcache.c

@@ -1380,8 +1380,11 @@ EXPORT_SYMBOL(d_set_d_op);
 static void __d_instantiate(struct dentry *dentry, struct inode *inode)
 {
 	spin_lock(&dentry->d_lock);
-	if (inode)
+	if (inode) {
+		if (unlikely(IS_AUTOMOUNT(inode)))
+			dentry->d_flags |= DCACHE_NEED_AUTOMOUNT;
 		list_add(&dentry->d_alias, &inode->i_dentry);
+	}
 	dentry->d_inode = inode;
 	dentry_rcuwalk_barrier(dentry);
 	spin_unlock(&dentry->d_lock);